Improper Update of Reference Count Affecting unbound package, versions [,1.25.1)
Threat Intelligence
The probability is the direct output of the EPSS model, and conveys an overall sense of the threat of exploitation in the wild. The percentile measures the EPSS probability relative to all known EPSS scores. Note: This data is updated daily, relying on the latest available EPSS model version. Check out the EPSS documentation for more details.
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Test your applications- Snyk IDSNYK-UNMANAGED-UNBOUND-17660948
- published28 Jun 2026
- disclosed20 May 2026
- creditUnknown
Introduced: 20 May 2026
CVE-2026-42534 (opens in a new tab)How to fix?
Upgrade unbound to version 1.25.1 or higher.
Overview
Affected versions of this package are vulnerable to Improper Update of Reference Count in the jostle process. An attacker can cause degraded resolution performance and potentially disrupt DNS resolution by controlling a malicious DNS server that responds slowly or maliciously to queries, thereby exploiting retransmitted queries to prevent proper replacement of slow-running queries.
Workaround
This vulnerability can be mitigated by restricting network exposure, configuring the service to only accept queries from trusted internal networks, and forwarding queries exclusively to trusted, well-maintained upstream DNS servers. A service restart is required after configuration changes.